A mobile or modifying communication device may have multiple antenna elements that transmit signals to communicate information. A base station or feedback communication device may extract information from the transmitted signals. Multiple antenna elements may enhance spatial or spectral efficiency, allowing for more users to be simultaneously served over a given frequency band. The transmitted signals, however, propagate along different paths and may reach the receiving communication device with different phases that destructively interfere. It is generally desirable to reduce interference of transmitted signals.
US Patent Publication No. 2003/0002594,assigned to the assignee of the present application, the contents of which are hereby incorporated herein by reference, describes using a power control signal, for example, as provided by the power control bit of the CDMA protocol, as a quality indication signal.